for a bulletin for millions of american shoppers. The retail giant target has issued a warning to their own customers to be on "the lookout" because they may be victims of a crime. Their credit card information stolen after shopping at target. Here's abc's chief business correspondent rebecca jarvis. Reporter: It's the question millions of americans are asking tonight, could their family's card have been compromised. It's incredibly frustrating. Going to targeting a weekend ritual in our house. Reporter: Chris and his family used their american express a few weeks ago and sent $62 at target. Now he fears he's one of those 40 million. We never expected anything like this would happen at a physical store. Reporter: Target tell abc news scammers got the names, account numbers and security codes of customers who visited target stores across the country. It's not exactly clear how the thieves did it but experts say the theft likely happened when shoppers swiped their cards to make a purchase. With the stolen information, the thieves can act in seconds. It's what happened to katie who asked that we not disclose her last name. They went to stores that I've never been to and successfully opened 11 to 14 different credit cards. Reporter: Those cooks going door to door and hitting nearly every store on this block on a $15,000 shopping spree, a $1200 macbook at best buy, sneakers, coats and fragrances at macy's in a matter of hours. Adam has fought identity thieves for decades. You can do everything right but if the wrong person gains unauthorized access, they have an option on your life. Reporter: EXPERTS Recommend checking your credit and bank statements and consider replacing your credit and debit cards if you used them recently at target. If there is fraud what percentage can you get back? everything but report that fraud, look at your account, go back to the bank, the credit card company, tell them it's fraud. They have an obligation to refund that back to you. So be sure to check into it quickly. Reporter: Very quickly. Thank you, rebecca jarvis. Tonight now we have the new

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